WASHINGTON — President Barack Obama and top Republican leaders will debate how to fix the US health care system Thursday in an unprecedented televised spectacle that could have more bearing on the political future of Obama and the Democrats than on how Americans pay for their doctors.

Obama goes into the event with little illusion that he can win over Republicans who have managed to block his sweeping health care overhaul package despite solid Democratic majorities in Congress.

But the president is looking to the forum to give his party a jolt ahead of the November congressional elections and revive its fading hopes for passing sweeping health care reform in the only develop nation without universal health care. Obama is trying to boost support not only from the American public, but also from moderate Democratic lawmakers, who could face the wrath of conservative voters if they back their president's plan.

Republicans have been wary of the meeting, but their top congressional leaders plan to attend. They have called on Obama to start over the whole process of reforming health care, but he has refused.

"We're happy to be there, but I'm not quite sure what the purpose is," said the Senate's top Republican, Minority Leader Mitch McConnell.

Obama will be the moderator for talks on four topics: revamping insurance, cost containment, expanding coverage and the impact of health care legislation on deficit reduction. The forum will take place in Blair House, the presidential guest quarters across from the White House, and be carried live on the C-Span cable network.

It's a sight Americans have never seen: the president and top congressional leaders from both parties seated together, sparring for six hours before a television camera.

The forum carries opportunities and risk for both sides.

Obama made health care the top priority of his first year as president, pushing for a plan that would extend coverage to tens of millions of people who are now uninsured.

Both chambers of Congress passed separate bills last year. But before the two versions could be reconciled, Republicans captured the Massachusetts Senate seat in a special election to replace the late Edward M. Kennedy. That cost Democrats the 60-vote supermajority needed to overcome Republican procedural obstacles and pass major legislation.

Public skepticism about the health care plan was seen as contributing to the Republican victory in Massachusetts, an overwhelmingly Democratic state. With the supermajority lost and Democrats getting nervous, the White House had been expected to shift its attention to job creation, an issue more likely to resonate with voters.

In pressing ahead with health care and holding the forum, Obama is taking a gamble. Passage of even a modest bill, which would now require complicated parliamentary maneuvers, would be a significant victory for Democrats. But if he fruitlessly presses ahead with health care amid lackluster public support, the Massachusetts race could foreshadow big losses in November.

For Republicans, the forum is an opportunity to keep the spotlight on an issue they've used to revive their political fortunes after huge losses in the 2006 and 2008 elections. They have cast Democratic proposals as a government takeover of health care that is likely to swell the budget and hurt the quality of care.

But at the forum, they risk being cast as obstructionists, unwilling to work with Democrats, at a time that many Americans are frustrated by Washington's partisan divide. Democrats have cast them as the "party of no," rejecting Obama's plan, but not offering a detailed alternative.

Yet many Republicans are also feeling pressure not to cooperate with Democrats. Conservative commentators and the "tea party" activists, who view big government as a threat to liberty, see compromise with Obama as a betrayal of Republican values. Some Republican lawmakers, including former presidential candidate John McCain, face primary challenges from more conservative opponents.

Obama also did not offer Republicans many signs of compromise on Monday when he unveiled his most detailed health care proposal to date. The plan, costing around $1 trillion over a decade, was similar to the Senate proposal that Republicans unanimously rejected.

Despite losing their supermajority, Democrats might still be able to pass major health legislation by using special budget rules that require only a simple majority. They have been reluctant to use that process so far because it would enrage Republicans and likely further worsen the partisan divide.

Even if they can get a bill through the Senate, Democrats are not assured of winning another vote in the House of Representatives, where a health bill was passed 220-215 in November. Some Democrats who supported the bill then say they will oppose it if they are not satisfied that it has adequate anti-abortion provisions.

Still, Democrats expressed confidence ahead of the forum.

Sen. Chris Dodd, who will be among the lawmakers participating, worked a rally of supporters.

"After that meeting, you can either join us or get out of the way," Dodd said. (AP)